I'm looking for virtualisation solutions for storage and OS for a home server. A sort of private cloud where I manage the storage space independently of the VM one.

This question focus on VM (or compute instance) management and what would best suit my needs. (I have another question related to the storage management).

My use cases are:

• A backup server: rsync and other services running.
• A personal cloud server: a kind of owned dropbox system, à la ownCloud. " users foreseen.
• A media server: streaming videos and displaying photos.

Here my environement and wishes:

• Server: HP Proliant MicroServer with 8 GB RAM (AMD Turion dual core with AMD-V technology)
• OS types: only Linux (perhaps a *BSD VM in the future)
• Linux distributions do not matter, I'm familiar with RHEL, Fedora, Suse, Ubuntu, but any other recommandation will be fine
• 2-3 VMs foreseen: backup server, owncloud server and media server (optional). Those are only servers, so no graphical console needed (I don't need VirtualBox)
• By VM I mean a virtualised environment like KVM, Xen, etc. or a compute instance like with OpenStack
• storage should be "virtualised/cloudified" see my other question.
• VM should be able to be migrated to another server in the future if performance cannot be fullfilled anymore by the current server
• It does not matter if installation of such setup is complicated as long as management tools allow for easy maintenance
• I don't have Windows at home, so solution should be Linux friendly and would be nice to be web based. But native apps are OK too.
• System should be easy to enhance: by adding a new server to migate some of the VMs to it. So it's really a kind of private cloud on which I could run some Linux OS.

I would prefer free (libre, as in a free speach) and open source tools. But it does not have to be free as in a free beer.

So Xen, KVM, VitualBox or OpenStack? What would you recommend?